How Probiotics Can Help You Be a Better Runner

By now you've heard of probiotics. But what exactly are they, and why are they good for runners? The bacteria found in some foods—the live cultures in yogurt, for example—are probiotics, which help balance the microbes in the intestines. These friendly bacteria have long been credited with easing bloating, gas, and other uncomfortable issues. Now, mounting evidence suggests that probiotics confer additional health benefits, including fighting off colds, improving heart health—and ending emergency midrun pit stops. "As more researchers test the various strains, the scientific data backing probiotics grows," says Mary Ellen Sanders, Ph.D., a consultant who helps food companies develop accurate health claims about the good-for-you bacteria.

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Probiotics form naturally during some fermentation processes, and some companies have begun fortifying foods with the good bacteria, making it easier than ever to get a daily dose. So load up your shopping cart with select yogurt and soy products, pickled vegetables, and other probiotic-laden foods to boost your health and your running in the following ways.

STOP THE PIT STOPSYour midrun need to find a bathroom—fast—could be the result of a condition that strikes endurance athletes, particularly runners, called leaky gut syndrome (the name does give a whole new meaning to the expression "gut-busting workout"). "One of the side effects of exercise is that it causes the cells lining the intestinal wall to pull apart a little bit," says Philip Calder, Ph.D., professor of nutritional immunology at the University of Southampton. Gaps between cells allow substances from the gastrointestinal tract to leak into the bloodstream, triggering various problems, including midworkout bowel distress.

Recent research suggests that probiotics can help correct the problem. One study that was published last year in the Journal of the International Society of Sports Nutrition analyzed blood samples from trained cyclists before and after intense exercise and found significantly fewer instances of leakage in athletes who'd taken probiotic supplements for 14 weeks. In a separate study, marathoners who consumed probiotics for three months prior to a race experienced shorter periods of GI trouble. Probiotics help keep gut cells together, which strengthens the intestinal wall, says Calder. And keeps runners out of the restroom.

BOLSTER YOUR IMMUNITYVitamin C has long been the go-to nutrient for boosting runners' immune systems during periods of hard training. Now, runners can also turn to probiotics. "There's pretty strong evidence that probiotics reduce the duration of upper respiratory infections and may even decrease how often they occur," says Sanders, citing research in Europe, China, and the U.S. In one study published in the British Journal of Sports Medicine, 20 elite distance runners who supplemented with probiotics during four months of winter training experienced milder symptoms and shorter bouts of respiratory illness. It's unclear exactly how probiotics fight invaders, Calder says, but studies indicate that the bacteria tell the immune system to work better.

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Runners in northwest Colorado provide anecdotal evidence. "I've seen improvements in my runners who start taking probiotic supplements or targeting probiotic foods," says Cara Marrs, R.D., a nutritionist, runner, and race director. "There's a huge reduction in mini-sicknesses, the two-day colds and GI bugs that are so common during a tough training cycle." She noted that even runners who do come down with something report that the bacteria seemed to help reduce the severity of their symptoms.

IMPROVE HEART, MOOD, WEIGHTThough the research is preliminary, studies suggest that probiotics' health benefits may have a broader reach. In research conducted at McGill University in Canada, subjects' LDL or "bad" cholesterol levels were 11.6 percent lower following nine weeks of probiotic supplementation. And studies conducted at UCLA and the University of Toronto have shown a link between probiotic intake and diminished anxiety. Additionally, studies with mice indicate probiotics could contribute to weight loss. Obese people have a different bacteria profile in the gut than lean individuals, says Calder. When mice had their gut bacterial makeup altered with probiotics, their weight changed. "You can actually make an obese animal lean, and vice versa, by swapping bacteria," says Calder, who adds that human clinical trials are still likely years away.

EAT WELL, MAYBE POP A PILLWhile researchers use supplements to isolate the effects of probiotics, runners can get a good health boost from food sources alone, says Marrs. But frequency is key: Probiotics in the gut die off quickly unless reinforcements arrive. Runners should aim for a daily dose from probiotic-rich foods. The time to consider a supplement is when you're running longer distances or feeling worn down, says Marrs. If you decide to pop a pill, look for products like Innate Response and New Chapter, which derive their probiotics from whole foods; these are better absorbed by the body.

And the usual good-food rules apply: Limit your intake of refined sugars and processed items, while also targeting fiber-rich foods. The combination helps boost the balance of friendly bacteria in your gut. "A healthy diet is primary," says Sanders. "Once you have that in place, probiotics may help."

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